Electronic mail,often abbreviated as email or e-mail,is a method of exchanging digital messages,designed primarily for human use.E-mail systems are based on a store-and-forward model in which e-mail computer server systems accept,forward,deliver and store messages on behalf of users,who only need to connect to the e-mail infrastructure,typically an e-mail server,with a network-enabled device (e.g.,a personal computer) for the duration of message submission or retrieval.Rarely is e-mail transmitted directly from one user's device to another's.An electronic mail message consists of two components,the message header,and the message body,which is the email's content.The message header contains control information,including,minimally,an originator's email address and one or more recipient addresses.Usually additional information is added,such as a subject header field.Originally a text-only communications medium,email is extended to carry multi-media content attachments,which were standardized in with RFC 2045 through RFC 2049,collectively called,Multipurpose Internet Mail Extensions (MIME).The foundation for today's global Internet e-mail service was created in the early ARPANET and standards for encoding of messages were proposed as early as,for example,in 1973 (RFC 561).An e-mail sent in the early 1970s looked very similar to one sent on the Internet today.Conversion from the ARPANET to the Internet in the early 1980s produced the core of the current service.Network-based email was initially exchanged on the ARPANET in extensions to the File Transfer Protocol (FTP),but is today carried by the Simple Mail Transfer Protocol (SMTP),first published as Internet Standard 10 (RFC 821) in 1982.In the process of transporting email messages between systems,SMTP communicates delivery parameters using a message envelope separately from the message (headers and body) itself.不知道难度是否适中啊~
最新问答: 设F1.F2分别是椭圆X^2/a^2+y^2/b^2=1的左右焦点,P是其右准线上纵坐标为根号3c,且F1F2=F2P, 为什么Qv=C△T 我在三师合编的无机化学找不到这条公式啊 英语翻译是涂料方向的 形容一个人本不是这个意思但又说成了这个意思的成语是什么? 方差已知的正太总体均值的检验要计算Z统计量.这句话是对事错 Grandma is watching TV (in the sitting-room.) 括号里的提问 地球半径为r,地球表面的重力加速度为g:若高空中某处的重力加速度为g/2,则该处距地面的高度为 A.(√2-1)r B. (2013•道里区模拟)一个棱长是6分米的正方体,它的占地面积是______平方分米,表面积是______平方分米,体积 有24盆花,摆成一个正方形.怎么摆? 翻译: 把肉放在切菜板上,把它切碎. ( )the meat ( ) the cutting board and ( ) 完璧归赵 完的意思 i don't know if we are going to che cinema or not.改错 用水清洗蔬菜上残留的农药,设用x(x≥1)单位量的水清洗一次以后,蔬菜上残留的农药量与本次清洗前残留的农药量之比为[1/ 甲苯易挥发吗 高中励志英语演讲 自信的含义及表现是什么?请分开答,谢谢! I don't want to change my (mind).I‘m (sleep)now.I want to go 阅读下面材料,请你对进一步改善北京空气质量提出两条建议。(2分) 真空中AB两个电荷,A的电荷是B的电荷量的4倍,则: 小明家5月份用电250千瓦时,其中用“峰电”150千瓦时,用谷电100千瓦时.请计算他们家使用峰电电价